How to convert Scala's List[Double] to java.util.List[java.lang.Double]?

Question

I have only seen examples where the result is a Java list of Scala doubles. I got as far as

def getDistance(): java.util.List[java.lang.Double] = {
  val javadistance = distance.toList.asJava
  javadistance
}

but this is still a Java list containing Scala doubles ( distance is a member of the same class as getDistance ).

Answer 1

One has to use the java boxed variant in a map:

  def getDistance(): java.util.List[java.lang.Double] = {
    distance.toList.map(Double.box).asJava
  }

Answer 2

Other than Scala 2.13+ box method, you can use:

def getDistance(): java.util.List[java.lang.Double] = {
  val javadistance = distance.toList.map(java.lang.Double.valueOf).asJava
  javadistance
}